commit vendor

vendor/sabre/event/lib/coroutine.php

@@ -0,0 +1,119 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Sabre\Event;
+
+use Generator;
+use Throwable;
+
+/**
+ * Turn asynchronous promise-based code into something that looks synchronous
+ * again, through the use of generators.
+ *
+ * Example without coroutines:
+ *
+ * $promise = $httpClient->request('GET', '/foo');
+ * $promise->then(function($value) {
+ *
+ *   return $httpClient->request('DELETE','/foo');
+ *
+ * })->then(function($value) {
+ *
+ *   return $httpClient->request('PUT', '/foo');
+ *
+ * })->error(function($reason) {
+ *
+ *   echo "Failed because: $reason\n";
+ *
+ * });
+ *
+ * Example with coroutines:
+ *
+ * coroutine(function() {
+ *
+ *   try {
+ *     yield $httpClient->request('GET', '/foo');
+ *     yield $httpClient->request('DELETE', /foo');
+ *     yield $httpClient->request('PUT', '/foo');
+ *   } catch(\Throwable $reason) {
+ *     echo "Failed because: $reason\n";
+ *   }
+ *
+ * });
+ *
+ * @return \Sabre\Event\Promise
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+function coroutine(callable $gen): Promise
+{
+    $generator = $gen();
+    if (!$generator instanceof Generator) {
+        throw new \InvalidArgumentException('You must pass a generator function');
+    }
+
+    // This is the value we're returning.
+    $promise = new Promise();
+
+    /**
+     * So tempted to use the mythical y-combinator here, but it's not needed in
+     * PHP.
+     */
+    $advanceGenerator = function () use (&$advanceGenerator, $generator, $promise) {
+        while ($generator->valid()) {
+            $yieldedValue = $generator->current();
+            if ($yieldedValue instanceof Promise) {
+                $yieldedValue->then(
+                    function ($value) use ($generator, &$advanceGenerator) {
+                        $generator->send($value);
+                        $advanceGenerator();
+                    },
+                    function (Throwable $reason) use ($generator, $advanceGenerator) {
+                        $generator->throw($reason);
+                        $advanceGenerator();
+                    }
+                )->otherwise(function (Throwable $reason) use ($promise) {
+                    // This error handler would be called, if something in the
+                    // generator throws an exception, and it's not caught
+                    // locally.
+                    $promise->reject($reason);
+                });
+                // We need to break out of the loop, because $advanceGenerator
+                // will be called asynchronously when the promise has a result.
+                break;
+            } else {
+                // If the value was not a promise, we'll just let it pass through.
+                $generator->send($yieldedValue);
+            }
+        }
+
+        // If the generator is at the end, and we didn't run into an exception,
+        // We're grabbing the "return" value and fulfilling our top-level
+        // promise with its value.
+        if (!$generator->valid() && Promise::PENDING === $promise->state) {
+            $returnValue = $generator->getReturn();
+
+            // The return value is a promise.
+            if ($returnValue instanceof Promise) {
+                $returnValue->then(function ($value) use ($promise) {
+                    $promise->fulfill($value);
+                }, function (Throwable $reason) use ($promise) {
+                    $promise->reject($reason);
+                });
+            } else {
+                $promise->fulfill($returnValue);
+            }
+        }
+    };
+
+    try {
+        $advanceGenerator();
+    } catch (Throwable $e) {
+        $promise->reject($e);
+    }
+
+    return $promise;
+}